Yes, Spelling and Grammar Do Matter
Unless you're creating a character who is uneducated and his writing is a factor in the story, don't be too creative with your spelling. The only place allowed for bad spelling and grammar will be in the actual writing that the character writes, not in his speech or narration. As the character improves his education, his spelling should show improvement. Don't let anyone convince you spelling and grammar doesn't matter. Ask any editor, publisher, or serious reader.
This is one fact that I cannot stress enough. No matter how well your story might be written, how thought-provoking the concept, nor how in-depth your characterization, bad spelling and grammar will turn off more readers than any other facet of your writing. Fortunately, spelling is one of the easiest problems to fix.
I don't write originals on-line. I use programs in the computer like WordPerfect (my personal favorite) or MS-Word/MS-Works. Open Office is a free program that does the job well. You need access to spelling correction, checking, and grammar help, and these programs do that. Windows Notepad and WordPad aren't your best choices because they don't have spell-check. There are good free choices that anyone can download, so not having a spell-checker is not an excuse for bad spelling.
Writing and storing locally, also assures that your original is always available in case your online one gets deleted accidentally--it happens frequently. Keeping copies of each revision is a good idea too, just in case you want to revert to an earlier version.
If you question a word, pull out a good dictionary. The point is, good spelling will encourage your readers not to stop reading at 250 words. (the first page)
Keep in mind that you won't catch everything. Some word processors also have grammar checkers. Use them, but don't depend on them. Their 'suggestions' are often comedic because they don't take context into consideration. This is an area you'll need to study on your own. There is nothing shameful about not being able to spell, nor to confuse your tenses. However, if you don't do anything about them, you're going to catch well-deserved flak, and you might consider that shameful.
Finally, after printing the work and reading from the paper (hard copy) a few times, correcting and changing things until you are satisfied you have a pretty good first draft, you can copy/paste/send the story to your writing group for feedback.
There are good reasons for this. You want your reviewers to spend their time going through your story with a sharp eye, looking for story elements and content to comment on, not fixing errors that your electronic checker could have caught. There will be missed errors enough, (there-their-they're--your and you're-- being the most common) that spellchecker won't catch. If two reviewers point to the same error, there should be no need for a third to find them in any future work. Fix them immediately, look them up in a grammar book or dictionary, study the differences and use them correctly from then on.
Spelling and grammar are not always easy to learn for English speakers, unless they were lucky enough to have very good teachers in their early school years. It's definitely not easy for those who have dyslexia, or are learning English as a second language. It's not always logical.
If you're using a word unfamiliar to you, look up the definition before you decide to keep it. Words mean different things according to how you're using it. If you're unsure of it's meaning, don't guess. Your style and voice are best brought out by using familiar words naturally.
Make a better first impression by preparing the work to be as reader friendly as you can. I know you do, but do it one more time. Some errors and typos are expected because no one set of eyes can catch them all. Just put some honest effort into finding them yourself. In my opinion, it's the only way to learn to use them correctly.
Another issue is white space. Add space between the paragraphs (as I've done here) to make it easier to read. It's the proper online format anyway and you may as well get used to it. Remember, lines of dialogue of each separate speaker are considered new paragraphs - space between them. It will be greatly appreciated by your readers and they will be able to concentrate on your story or poem.
The bottom line is, you want feedback on the story elements, not just the pointing out of spelling/grammar errors. Just because it can be 'figured out' enough to be understood doesn't make it a publishable, acceptable, enjoyable write for anyone except the writer.
Make a good first impression.
Thanks for reading,